Cassettes of this kind are known for example from U.S. Pat. No. 4,572,461, GB Nos. 2,155,905, GB 2,167,386, EP No. 0 160 822 and GB No. 2 165 819. A magnetic tape cassette of that kind is represented in perspective in FIG. 1. The cassette consists of an upper casing half (1), comprising a back wall (2), side walls (3) running in parallel and a right-angled cover plate. A window opening (4) is provided in the middle of the cover plate, running in a longitudinal direction. This enables the state of winding of the magnetic tape to be observed. A lower casing half (5) contains in the middle part of its lower base plate two symmetrically placed openings (14), into which the drive shafts of the recorder for the spools (6a,6b) are placed. The side walls and back walls of the upper and lower casing halves are essentially equal in height. If the upper and lower casing halves are mounted on one another, a casing space is formed in between. The spools (6a,6b) serving to wind and unwind the magnetic tape (7) are symmetrically arranged in the middle region of this casing space. Toothing is provided at the upper or lower end regions of the hubs. Slide foils (8a,8b) are arranged on both sides of the spools, so that easy sliding of the magnetic tape is guaranteed. A spool brake (9) locks the toothing of the hubs. The open space (10) formed between the upper and lower halves of the casing after assembly is sealed by a front flap (11), in order to prevent dust from penetrating into the cassette casing. Undrawn drive elements of a tape drive device reach into the open space. The front flap consists of a longitudinal front surface with a section slightly bent upwards and side (12) arranged at both ends. The front flap is swivellably mounted on the cassette casing by mounting pins (13) projecting from the inner surfaces of the side. A slide (15) is provided for covering the open space of the lower half of the casing, in order to prevent the penetration of dust through the opening (14). The slide comprises side walls (16) of equal height that run in parallel and a rectangular plate for connecting both side walls. Symmetrically placed openings (17) are provided in the middle region of the slide, through which the recorder-side drive shaft can reach to the spool hubs if the slide is in the rear position when the magnetic tape cassette is in open position. The slide is pre-stressed by a (not drawn) spring, whose bent-away end is fixed in the post (23) at the lower half of the casing and whose free end rests at the projection (19) on the slide. Another embodiment, which is described in GB No. 2 155 905 that has already been mentioned, provides a screw spring, for prestressing the slide, whose front part is supported by a projection in the cassette part and whose rear part is supported by a projection of the slide, and which is guided in a slit provided in the lower half of the casing.
In a magnetic tape cassette of this kind, the front part of the cassette casing is closed by the front flap (11) when not in use, which can be seen from FIG. 2, and the sliding slide is slid forward in such a manner that the cut-out region of the spool shaft inlet openings (14) is sealed by the slide, which moves in the direction of the arrow. The magnetic tape is thereby completely protected in the cassette casing.
However, the above construction also results in that during use of the cassette both the front flap and the slide must be activated, which occurs by relevant recorder-side means.
EP NO. 0 150 987 set as its object the coupling of activation of the front flap and of the slide of the magnetic tape cassette, which is effected by two toothed racks applied to be both sides of the slide, with which the toothed wheel segments connected with the front flap mesh. Such a magnetic tape cassette is, however, difficult to produce and to assemble, as the arrangement of toothed rack and toothed wheel segment presents problems during joining.